What is the duration that defines a long term radon test?

A long-term radon test is defined as one that is conducted over a duration of 91 days or longer. This duration is significant because it allows for a more accurate assessment of radon levels that may fluctuate over shorter periods. A minimum testing time of 91 days captures variations in radon concentrations that can occur due to changes in weather, ventilation, and building occupancy, which short-term tests might miss.

Long-term tests provide a clearer picture of the average radon exposure that occupants may experience throughout different conditions, aiding in effective risk assessment. In contrast, shorter testing periods, such as those mentioned in other choices, may not provide a comprehensive understanding of a home's radon levels over time. Thus, the focus on 91 days or longer ensures that test results reflect an average over time, aligning with industry standards and safety guidelines for radon measurement.